Turns out the user was set to `jboss` in the base image.  
When is switched to user root with the dockerfile command `USER root` everything worked. 


The docker-compose file https://docs.docker.com/compose/compose-file/#/volumes-volume-driver shows various ways to mount host sub-directories relative to the compose file.

For example:

```yaml
volumes:
   # Just specify a path and let the Engine create a volume
   - /var/lib/mysql
 
   # Specify an absolute path mapping
   - /opt/data:/var/lib/mysql
 
   # Path on the host, relative to the Compose file
   - ./cache:/tmp/cache
 
   # User-relative path
   - ~/configs:/etc/configs/:ro
 
   # Named volume
   - datavolume:/var/lib/mysql
```

Is is possible to mount a sub-directory of a named volume at a specific location?  For example something like below, which I tried, but does not seem to work.

    # Named volume
      - datavolume/sql_data:/var/lib/mysql

I am assuming I might be able to manage this by mounting the data volume to a location like `/data` and then in the Dockerfiles for each container, create symbolic links from the sub-directories to the locations.

for example in a docker-compose.yml file

    volumes:
      - datavolume:/data

and then in the container Dockerfile

    RUN ln -s /data/sql_data /var/lib/mysql

I started going down this path but it was getting messy and was not working.  Before I either abandon that approach or invest the time debugging it, I wanted to make sure there was no way to just specify sub-directories of a named vollume. 

Can we mount sub-directories of a named volume in docker?

I am using Vuejs and I keep getting this warning in the console. Also no data is loaded because of this warning. I checked the code for unwanted tags but did not find any.

Is this because of the javascript code or I have something wrong in my html?

 Here is my code:

&gt; HTML

    &lt;div class=&quot;row&quot;&gt;
        &lt;div class=&quot;col-sm-12&quot; style=&quot;margin-top: 20px;&quot;&gt;
            &lt;form class=&quot;form-inline&quot; method=&quot;GET&quot; action=&quot;.&quot;&gt;
                &lt;div class=&quot;col-sm-3&quot; style=&quot;float: right;&quot;&gt;&lt;h4&gt;Date:&lt;/h4&gt;
                    &lt;input class=&quot;form-control&quot; style=&quot;padding-bottom:0px;&quot; type=&quot;text&quot; id=&quot;datepicker&quot; readonly=&quot;true&quot; name=&quot;date&quot; value=&quot;2016-06-30&quot;&gt;
                    &lt;input type=&quot;submit&quot; class=&quot;btn btn-primary btn-sm&quot; value=&quot;Submit&quot; &gt;
                &lt;/div&gt;
                
            &lt;/form&gt;
            &lt;div class=&quot;col-sm-2&quot; style=&quot;float: right; margin-top:40px;&quot;&gt;
                &lt;button class=&quot;btn btn-info&quot; type=&quot;button&quot; id=&quot;csv_export&quot;&gt;Click to Export&lt;/button&gt;
            &lt;/div&gt;
        &lt;/div&gt;
        &lt;div class=&quot;col-sm-12&quot; style=&quot;margin:20px;&quot;&gt;
            &lt;table class=&quot;table table-sm table-striped table-bordered&quot; id=&quot;absent-list&quot;&gt;
                &lt;thead&gt;
                    &lt;tr&gt;
                        &lt;th&gt;#&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Full Name&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Section&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Person Called&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Person Relation&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Phone Number&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Absent Reason&lt;/th&gt;
                        &lt;th style=&quot;text-align: center; font-size: 15px;&quot;&gt;Remarks&lt;/th&gt;
                        &lt;th&gt;&lt;/th&gt;
                    &lt;/tr&gt;
                &lt;/thead&gt;
                &lt;tbody&gt;
                    &lt;tr v-show=&quot;loading&quot; class=&quot;text-center&quot;&gt;
                        &lt;td colspan=&quot;7&quot;&gt;
                            &lt;i class=&quot;fa fa-spinner fa-spin fa-4x&quot;&gt;&lt;/i&gt;
                        &lt;/td&gt;
                    &lt;/tr&gt;
                    &lt;tr v-for=&quot;record in absent_followback_records&quot;&gt;
                        
                        &lt;td style=&quot;text-align: center; font-size: 15px;&quot; scope=&quot;row&quot;&gt; {{$index + 1}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center; font-size: 15px;&quot;&gt;{{record.student_name}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center; font-size: 15px;&quot;&gt;{{record.student_section}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;{{record.person_called}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;{{record.person_relation}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;{{record.phone_number}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;{{record.absent_reason_name}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;{{record.remarks}}&lt;/td&gt;
                        &lt;td  style=&quot;text-align: center;&quot;&gt;&lt;a href=&quot;#&quot; v-on:click=&quot;editAbsentFollowbackRecord($index)&quot; data-toggle=&quot;modal&quot; data-target=&quot;#absent-followback-edit&quot;&gt; Edit &lt;/a&gt;&lt;/td&gt;
                        
                    &lt;/tr&gt;
                &lt;/tbody&gt;
            &lt;/table&gt;
            
        &lt;/div&gt;
    &lt;/div&gt;
    
    &lt;script src=&quot;/static/js/jquery-ui.min.js&quot;&gt;&lt;/script&gt;
    &lt;script src=&quot;/static/js/jquery.plugin.min.js&quot;&gt;&lt;/script&gt; 
    &lt;script src=&quot;/static/js/jquery.datepick.min.js&quot;&gt;&lt;/script&gt;
    &lt;script src=&quot;https://cdn.jsdelivr.net/vue/latest/vue.js&quot;&gt;&lt;/script&gt;
    &lt;script src=&quot;/static/js/csrftoken.js&quot;&gt;&lt;/script&gt;
    &lt;script src=&quot;/static/js/jquery.TableCSVExport.js&quot;&gt;&lt;/script&gt;
    
    &lt;script type=&quot;text/javascript&quot;&gt;
    
        var absentFollowbackListAPiUrl = &quot;/student/api/absent/followback/list/11/&quot;;
        var absent_reason = jQuery.parseJSON(&#39;[{&quot;model&quot;: &quot;studentprofile.absentreason&quot;, &quot;pk&quot;: 1, &quot;fields&quot;: {&quot;created&quot;: &quot;2016-05-08T06:09:42.410Z&quot;, &quot;modified&quot;: &quot;2016-05-08T06:09:42.410Z&quot;, &quot;reason_name&quot;: &quot;sick&quot;}}, {&quot;model&quot;: &quot;studentprofile.absentreason&quot;, &quot;pk&quot;: 2, &quot;fields&quot;: {&quot;created&quot;: &quot;2016-05-08T06:09:42.416Z&quot;, &quot;modified&quot;: &quot;2016-05-08T06:09:42.416Z&quot;, &quot;reason_name&quot;: &quot;arrived late&quot;}}, {&quot;model&quot;: &quot;studentprofile.absentreason&quot;, &quot;pk&quot;: 3, &quot;fields&quot;: {&quot;created&quot;: &quot;2016-05-08T06:09:42.419Z&quot;, &quot;modified&quot;: &quot;2016-05-08T06:09:42.419Z&quot;, &quot;reason_name&quot;: &quot;work at home&quot;}}, {&quot;model&quot;: &quot;studentprofile.absentreason&quot;, &quot;pk&quot;: 4, &quot;fields&quot;: {&quot;created&quot;: &quot;2016-05-08T06:09:42.423Z&quot;, &quot;modified&quot;: &quot;2016-05-08T06:09:42.423Z&quot;, &quot;reason_name&quot;: &quot;public holiday&quot;}}]&#39;);
        var profile_value = false;
        
    &lt;/script&gt;
    &lt;script type=&quot;text/javascript&quot; src=&quot;/static/js/student/student-followback.js&quot;&gt;&lt;/script&gt;

&gt; absent-followback.js file

    $(function() {
        $( &quot;#datepicker&quot; ).datepick({dateFormat: &#39;yyyy-mm-dd&#39;});
    });
    
    $(&#39;#csv_export&#39;).click(function (e) {
        e.preventDefault();
        $(&#39;#absent-list&#39;).TableCSVExport({
            delivery: &#39;download&#39;,
            filename: &#39;absent-list(&#39; + $( &quot;#datepicker&quot; ).val() + &#39;).csv&#39;
        });
    });
    
    var vm = new Vue({
            el: &#39;body&#39;,
            data: {
                absent_followback_records: [],
                followbackRecordIndex: &#39;off&#39;,
                absentReasonList: absent_reason,
                loading: false,
                currentData: {},
                profile: profile_value,
                listApiUrl: absentFollowbackListAPiUrl
            },
            methods: {
                populateData: function(api_url){
                    var self = this;
                    $.get(api_url, function(data){
                        self.absent_followback_records = data;
                        self.loading = false;
                    });
                },
                getAbsentFollowbackRecord: function () {
                    var self = this;
                    self.loading = true;
                    var date = $( &quot;#datepicker&quot; ).val();
                    var api_url = self.listApiUrl + &#39;?date=&#39; + date;
                    self.populateData(api_url);
                },
                getProfileAbsentFollowbackRecord: function (event) {
                    var self = this;
                    self.loading = true;
                    var expanded = $(event.target).attr(&#39;aria-expanded&#39;);
                    if (expanded == &#39;false&#39;){
                        $(event.target).html(&#39;Hide Details&#39;);
                        var studentId = $(event.target).attr(&#39;studentId&#39;);
                        var api_url = self.listApiUrl + &#39;?student_id=&#39; + studentId;
                        self.populateData(api_url);
                    }
                    else{
                        $(event.target).html(&#39;Show Details&#39;);
                    }
                },
                editAbsentFollowbackRecord: function (followbackRecordIndex) {
                    var self = this;
                    self.currentData = self.absent_followback_records[followbackRecordIndex];
                    self.followbackRecordIndex = followbackRecordIndex;
                },
                updateAbsentFollowbackRecord: function (followbackRecordIndex){
                    var self = this;
                    var updateData = self.currentData;
                    var absent_date = updateData.date;
                    var student_id = updateData.student;
                    var post_url = updateData.update_url;
                    var person_called = updateData.person_called;
                    var person_relation = updateData.person_relation;
                    var phone_number = updateData.phone_number;
                    var absent_reason = updateData.absent_reason;
                    var remarks = updateData.remarks;
                    if (person_called){
                        var data = {
                            student: parseInt(student_id),
                            date: absent_date,
                            person_called: person_called,
                            person_relation: person_relation,
                            phone_number: phone_number,
                            absent_reason: parseInt(absent_reason),
                            remarks: remarks
                        };
                        $(&#39;#updateAbsentFollowback&#39;).html(&#39;&lt;i class=&quot;fa fa-spinner fa-spin&quot;&gt;&lt;/i&gt; Saving&#39;).attr(&#39;class&#39;, &#39;btn btn-primary disabled&#39;);
                        $.ajax({
                            url: post_url,
                            type: &quot;PUT&quot;,
                            data: JSON.stringify(data),
                            dataType: &#39;json&#39;,
                            contentType: &quot;application/json&quot;,
                            success: function(responseData) {
                                $(&#39;#updateAbsentFollowback&#39;).html(&#39;Save&#39;).attr(&#39;class&#39;, &#39;btn btn-success&#39;);
                                if (self.profile == true){
                                    api_url = self.listApiUrl + &#39;?student_id=&#39; + student_id;
                                    self.populateData(api_url);
                                }
                                else{
                                    self.getAbsentFollowbackRecord();
                                }
                            },
                            error: function( xhr, status, errorThrown ) {
                            console.log(errorThrown);
                            }
                        });
                    }
                }
    
            },
            ready() {
                if (this.profile != true){
                    this.getAbsentFollowbackRecord();
                }
            }
        })

Error: Templates should only be responsible for mapping the state to the UI. Avoid placing tags with side-effects in your templates, such as &lt;script&gt;

I am unable to run any yum commands inside my Docker container without getting the following error:

    ovl: Error while doing RPMdb copy-up:
    [Errno 13] Permission denied: &#39;/var/lib/rpm/Group&#39;
    You need to be root to perform this command.

I&#39;m confused because I&#39;m pretty sure docker containers are run with the default user root.  Still, if I try putting sudo in front of a `yum install -y &lt;package&gt;` or `yum update -y` command I get:

    /bin/sh: sudo: command not found

I&#39;m using the following base image so I can easily run a Java Wildfly application inside Docker: https://hub.docker.com/r/jboss/wildfly/

The underlying distro is `CentOS Linux release 7.2.1511 (Core)`


Can&#39;t use yum inside Docker container running on CentOS

I am unable to run any yum commands inside my Docker container without getting the following error:
<pre><code class="hljs language-vbnet">ovl: Error while doing RPMdb copy-up:
[Errno 13] Permission denied: '/var/lib/rpm/Group'
You need to be root to perform this command.
</code></pre>
I'm confused because I'm pretty sure docker containers are run with the default user root. Still, if I try putting sudo in front of a <code>yum install -y &#x3C;package></code> or <code>yum update -y</code> command I get:
<pre><code class="hljs language-bash">/bin/sh: sudo: command not found
</code></pre>
I'm using the following base image so I can easily run a Java Wildfly application inside Docker: <a href="https://hub.docker.com/r/jboss/wildfly/" target="_blank" rel="noopener noreferrer">https://hub.docker.com/r/jboss/wildfly/</a>
The underlying distro is <code>CentOS Linux release 7.2.1511 (Core)</code>

How to restart all running docker containers? Mainly looking for a shortcut instead of doing 

&gt; docker restart containerid1 containerid2

Command for restarting all running docker containers?

## Problem ##
I&#39;m trying to start postgres in a docker container on my Mac, but I keep getting the following error message

&gt; docker: Error response from daemon: driver failed programming external connectivity on endpoint postgres (8392b9e5cfaa28f480fe1009dee461f97e82499726f4afc4e916358dd2d2f61e): Error starting userland proxy: Failed to bind tcp 0.0.0.0:5432 address already in use.

I have postgres installed locally, but I stopped it and running 

    pg_ctl status

returns 
&gt;pg_ctl: no server running

I&#39;ve ran the following to check what&#39;s running on 5432 

    lsof -i tcp:5432

&amp;

    netstat -anp tcp | grep 5432

and nothing is running on the port.

## Versions ##

Mac - OS X El Capitan Version 10.11.2

PostgreSQL - 9.5 

Docker - Docker version 1.12.0-rc2, build 906eacd, experimental


Docker &amp; Postgres: Failed to bind tcp 0.0.0.0:5432 address already in use

I want to update my `/etc/hosts` file during &quot;docker build&quot;.

I added below line in Dockerfile but it&#39;s neither updating `/etc/hosts` file nor giving any error.

    RUN echo &quot;192.168.33.11    mynginx&quot; &gt;&gt; /etc/hosts

I need to update `/etc/hosts`. Can anyone suggest on this?

How to update /etc/hosts file in Docker image during &quot;docker build&quot;

I&#39;ve a service listening to 8080 port. This one is not a container.

Then, I&#39;ve created a nginx container using official image:

    docker run --name nginx -d -v /root/nginx/conf:/etc/nginx/conf.d -p 443:443 -p 80:80 nginx

After all:

    # netstat -tupln | grep 443
    tcp6       0      0 :::443                  :::*                    LISTEN      3482/docker-proxy
    # netstat -tupln | grep 80
    tcp6       0      0 :::80                   :::*                    LISTEN      3489/docker-proxy
    tcp6       0      0 :::8080                 :::*                    LISTEN      1009/java

Nginx configuration is:


    upstream eighty {
        server 127.0.0.1:8080;
    }

    server {
        listen 80;
        server_name eighty.domain.com;
    
        location / {
          proxy_pass                        http://eighty;
        }
    }


I&#39;ve checked I&#39;m able to connect with with this server with `# curl http://127.0.0.1:8080`

     &lt;html&gt;&lt;head&gt;&lt;meta http-equiv=&#39;refresh&#39;
     content=&#39;1;url=/login?from=%2F&#39;/&gt;&lt;script&gt;window.location.replace(&#39;/login?from=%2F&#39;);&lt;/script&gt;&lt;/head&gt;&lt;body
     style=&#39;background-color:white; color:white;&#39;&gt;
     ...

It seems running well, however, when I&#39;m trying to access using my browser, nginx tells bt a 502 bad gateway response.

I&#39;m figuring out it can be a problem related with the visibility between a open by a non-containerized process and a container. Can I container stablish connection to a port open by other non-container process?


**EDIT**

Logs where `upstream { server 127.0.0.1:8080; }`:

    2016/07/13 09:06:53 [error] 5#5: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 62.57.217.25, server: eighty.domain.com, request: &quot;GET / HTTP/1.1&quot;, upstream: &quot;http://127.0.0.1:8080/&quot;, host: &quot;eighty.domain.com&quot;
    62.57.217.25 - - [13/Jul/2016:09:06:53 +0000] &quot;GET / HTTP/1.1&quot; 502 173 &quot;-&quot; &quot;Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0&quot; &quot;-&quot;

Logs where `upstream { server 0.0.0.0:8080; }`:

    62.57.217.25 - - [13/Jul/2016:09:00:30 +0000] &quot;GET / HTTP/1.1&quot; 502 173 &quot;-&quot; &quot;Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0&quot; &quot;-&quot; 2016/07/13 09:00:30 [error] 5#5: *1 connect() failed (111: Connection refused) while connecting to upstream, client:
    62.57.217.25, server: eighty.domain.com, request: &quot;GET / HTTP/1.1&quot;, upstream: &quot;http://0.0.0.0:8080/&quot;, host: &quot;eighty.domain.com&quot; 2016/07/13 09:00:32 [error] 5#5: *3 connect() failed (111: Connection refused) while connecting to upstream, client: 62.57.217.25, server: eighty.domain.com, request: &quot;GET / HTTP/1.1&quot;, upstream: &quot;http://0.0.0.0:8080/&quot;, host: &quot;eighty.domain.com&quot;
    62.57.217.25 - - [13/Jul/2016:09:00:32 +0000] &quot;GET / HTTP/1.1&quot; 502 173 &quot;-&quot; &quot;Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0&quot; &quot;-&quot;

Any ideas?

nginx docker container: 502 bad gateway response

I&#39;m running Docker on CentOS 7, from time to time there&#39;s the following message displayed:

    Message from syslogd@dev-master at Mar 29 17:23:03 ...
      kernel:unregister_netdevice: waiting for lo to become free. Usage count = 1

I&#39;ve googled a lot, read a lot of resources found and tried many ways like keeping my system updated, upgrading kernel etc, but the message still keeps showing up, it&#39;s not too often but sooner or later I&#39;ll see it. Also I found [issue for this problem on docker github][1] is still open, then my questions are:

1. What does this message mean? Could somebody give me a simple explanation why docker causes it?
2. Is there any workaround for this?
3. If it could not be fixed yet(the issue is still open), will it affect the server or services running inside docker container? Will it be a serious performance issue because it also happens on our production servers? 

Docker version:

    Client:
     Version:      1.11.1
     API version:  1.23
     Go version:   go1.5.4
     Git commit:   5604cbe
     Built:        Wed Apr 27 00:34:42 2016
     OS/Arch:      linux/amd64

    Server:
     Version:      1.11.1
     API version:  1.23
     Go version:   go1.5.4
     Git commit:   5604cbe
     Built:        Wed Apr 27 00:34:42 2016
     OS/Arch:      linux/amd64

OS info: 

    CentOS 7, with kernel version: 4.6.0-1.el7.elrepo.x86_64

I really appreciate for any info/tips or resources, thanks a lot. 


  [1]: https://github.com/docker/docker/issues/5618

Docker on CentOS 7.2: kernel:unregister_netdevice: waiting for lo to become free. Usage count = 1

I am trying to run a [CentOS][1] 8 server through [VirtualBox][2] (6.1.30) ([Vagrant][3]), which worked just fine yesterday for me, but today I tried running a `sudo yum update`. I keep getting this error for some reason:

    [vagrant@192.168.38.4] ~  &gt;&gt; sudo yum update
    CentOS Linux 8 - AppStream                       71  B/s |  38  B     00:00
    Error: Failed to download metadata for repo &#39;appstream&#39;: Cannot prepare internal mirrorlist: No URLs in mirrorlist

I already tried to change the namespaces on `/etc/resolve.conf`, remove the [DNF][4] folders and everything. On other computers, this works just fine, so I think the problem is with my host machine. I also tried to reset the network settings (I am on a Windows&amp;nbsp;10 host), without success either. It&#39;s not a DNS problem; it works just fine.

After I reinstalled Windows, I still have the same error in my VM.

File *dnf.log*:

    2022-01-31T15:28:03+0000 INFO --- logging initialized ---
    2022-01-31T15:28:03+0000 DDEBUG timer: config: 2 ms
    2022-01-31T15:28:03+0000 DEBUG Loaded plugins: builddep, changelog, config-manager, copr, debug, debuginfo-install, download, generate_completion_cache, groups-manager, needs-restarting, playground, repoclosure, repodiff, repograph, repomanage, reposync
    2022-01-31T15:28:03+0000 DEBUG YUM version: 4.4.2
    2022-01-31T15:28:03+0000 DDEBUG Command: yum update
    2022-01-31T15:28:03+0000 DDEBUG Installroot: /
    2022-01-31T15:28:03+0000 DDEBUG Releasever: 8
    2022-01-31T15:28:03+0000 DEBUG cachedir: /var/cache/dnf
    2022-01-31T15:28:03+0000 DDEBUG Base command: update
    2022-01-31T15:28:03+0000 DDEBUG Extra commands: [&#39;update&#39;]
    2022-01-31T15:28:03+0000 DEBUG User-Agent: constructed: &#39;libdnf (CentOS Linux 8; generic; Linux.x86_64)&#39;
    2022-01-31T15:28:05+0000 DDEBUG Cleaning up.
    2022-01-31T15:28:05+0000 SUBDEBUG
    Traceback (most recent call last):
      File &quot;/usr/lib/python3.6/site-packages/dnf/repo.py&quot;, line 574, in load
        ret = self._repo.load()
      File &quot;/usr/lib64/python3.6/site-packages/libdnf/repo.py&quot;, line 397, in load
        return _repo.Repo_load(self)
    libdnf._error.Error: Failed to download metadata for repo &#39;appstream&#39;: Cannot prepare internal mirrorlist: No URLs in mirrorlist

    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File &quot;/usr/lib/python3.6/site-packages/dnf/cli/main.py&quot;, line 67, in main
        return _main(base, args, cli_class, option_parser_class)
      File &quot;/usr/lib/python3.6/site-packages/dnf/cli/main.py&quot;, line 106, in _main
        return cli_run(cli, base)
      File &quot;/usr/lib/python3.6/site-packages/dnf/cli/main.py&quot;, line 122, in cli_run
        cli.run()
      File &quot;/usr/lib/python3.6/site-packages/dnf/cli/cli.py&quot;, line 1050, in run
        self._process_demands()
      File &quot;/usr/lib/python3.6/site-packages/dnf/cli/cli.py&quot;, line 740, in _process_demands
        load_available_repos=self.demands.available_repos)
      File &quot;/usr/lib/python3.6/site-packages/dnf/base.py&quot;, line 394, in fill_sack
        self._add_repo_to_sack(r)
      File &quot;/usr/lib/python3.6/site-packages/dnf/base.py&quot;, line 137, in _add_repo_to_sack
        repo.load()
      File &quot;/usr/lib/python3.6/site-packages/dnf/repo.py&quot;, line 581, in load
        raise dnf.exceptions.RepoError(str(e))
    dnf.exceptions.RepoError: Failed to download metadata for repo &#39;appstream&#39;: Cannot prepare internal mirrorlist: No URLs in mirrorlist
    2022-01-31T15:28:05+0000 CRITICAL Error: Failed to download metadata for repo &#39;appstream&#39;: Cannot prepare internal mirrorlist: No URLs in mirrorlist

  [1]: https://en.wikipedia.org/wiki/CentOS
  [2]: https://en.wikipedia.org/wiki/VirtualBox
  [3]: https://en.wikipedia.org/wiki/Vagrant_%28software%29
  [4]: https://en.wikipedia.org/wiki/DNF_(software)


CentOS through a VM - no URLs in mirrorlist

What is the username/password/keys to ssh into the Minikube VM?


How do I ssh into the VM for Minikube?

*(Post created on Oct 05 &#39;16)*

I noticed that every time I run an image and delete it, my system doesn&#39;t return to the original amount of available space.

The lifecycle I&#39;m applying to my containers is:

    &gt; docker build ...
    &gt; docker run CONTAINER_TAG
    &gt; docker stop CONTAINER_TAG
    &gt; rm docker CONTAINER_ID
    &gt; rmi docker image_id

*[ running on a default mac terminal ]*

The containers in fact were created from custom images, running from node and a standard redis. My OS is OSX 10.11.6.

At the end of the day I see I keep losing Mbs. How can I face this problem?

**EDITED POST**

2020 and the problem persists, leaving this update for the community:

Today running:

- macOS 10.13.6
- Docker Engine 18.9.2
- Docker Desktop Cli 2.0.0.3

The easiest way to workaround the problem is to prune the system with the Docker utilties.

    docker system prune -a --volumes


Docker filling up storage on macOS

Is it possible to install any version of Visual Studio in a [Windows Container][1] on a Windows Server?

The motivation is to use Windows Containers for building software in continuous integration systems, so that the build environment is standardized.

  [1]: https://docs.microsoft.com/sv-se/virtualization/windowscontainers/quick-start/quick-start-windows-server

Is it possible to install Visual Studio in a Windows Container

**Question 1** - I&#39;m reading the documentation and I&#39;m slightly confused with the wording. It says:

&gt; **ClusterIP**: Exposes the service on a cluster-internal IP. Choosing this value makes the service only reachable from within the cluster. This is the default ServiceType
&gt; 
&gt; **NodePort**: Exposes the service on each Node’s IP at a static port (the NodePort). A ClusterIP service, to which the NodePort service will route, is automatically created. You’ll be able to contact the NodePort service, from outside the cluster, by requesting `&lt;NodeIP&gt;:&lt;NodePort&gt;`.
&gt; 
&gt; **LoadBalancer**: Exposes the service externally using a cloud provider’s load balancer. NodePort and ClusterIP services, to which the external load balancer will route, are automatically created.

Does the NodePort service type still use the `ClusterIP` but just at a different port, which is open to external clients? So in this case is `&lt;NodeIP&gt;:&lt;NodePort&gt;` the same as `&lt;ClusterIP&gt;:&lt;NodePort&gt;`?

Or is the `NodeIP` actually the IP found when you run `kubectl get nodes` and not the virtual IP used for the ClusterIP service type?

**Question 2** - Also in the diagram from the link below:

[![enter image description here][1]][1]

Is there any particular reason why the `Client` is inside the `Node`? I assumed it would need to be inside a `Cluster`in the case of a ClusterIP service type?

If the same diagram was drawn for NodePort, would it be valid to draw the client completely outside both the `Node` and`Cluster` or am I completely missing the point?


  [1]: https://i.stack.imgur.com/P36yL.png

What&#39;s the difference between ClusterIP, NodePort and LoadBalancer service types in Kubernetes?

I would like to deploy an application cluster by managing my deployment via k8s Deployment object. The documentation has me extremely confused. My basic layout has the following components that scale independently:

 1. API server
 2. UI server
 3. Redis cache
 4. Timer/Scheduled task server

Technically, all 4 above belong in separate pods that are scaled independently. 

My questions are:

 1. Do I need to create `pod.yml` files and then somehow reference them in `deployment.yml` file or can a deployment file also embed pod definitions?
 2. K8s documentation seems to imply that the `spec` portion of `Deployment` is equivalent to defining *one* pod. Is that correct? What if I want to declaratively describe multi-pod deployments? Do I do need multiple deployment.yml files?

How to configure a Kubernetes Multi-Pod Deployment

I have installed TensorFlow using the following command 

    docker run -it b.gcr.io/tensorflow/tensorflow:latest-devel

and I need to set up TensorFlow Serving on a windows machine. I followed [the instructions](https://github.com/tensorflow/serving/blob/master/tensorflow_serving/g3doc/setup.md) and while running the below-mentioned `sudo` command while installing TensorFlow Serving dependencies:

    sudo apt-get update &amp;&amp; sudo apt-get install -y \
         build-essential \
         curl \
         git \
         libfreetype6-dev \
         libpng12-dev \
         libzmq3-dev \
         pkg-config \
         python-dev \
         python-numpy \
         python-pip \
         software-properties-common \
         swig \
         zip \
         zlib1g-dev

The following error is displayed:

    bash: sudo: command not found

Unable to use sudo commands within Docker, &quot;bash: sudo: command not found&quot; is displayed

I&#39;m trying to install [Prestissimo][1] to an Ubuntu 16.04 server, but that leads to an error:

    $ composer global require &quot;hirak/prestissimo:^0.3&quot;
    Changed current directory to /home/kramer65/.composer
    
    
      [ErrorException]
      file_put_contents(./composer.json): failed to open stream: Permission denied
    
    
    require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--] [&lt;packages&gt;]...

I&#39;m logged in as user `kramer65`, so I wouldn&#39;t know why it can&#39;t write to my home folder. My normal reaction to a `permission denied` is to use `sudo`, but composer then always says:

&gt; Do not run Composer as root/super user! See https://getcomposer.org/root for details

Any idea how I can solve this?

  [1]: https://github.com/hirak/prestissimo

Composer: file_put_contents(./composer.json): failed to open stream: Permission denied

After trying to install virtualenv with pip

    $ pip install virtualenv

I got a permission denied error

    IOError: [Errno 13] Permission denied: &#39;/Library/Python/2.7/site-packages/virtualenv.py&#39;

So I used sudo to install virtualenv

    $ sudo pip install virtualenv

But then a warning showed up:

&gt; The directory &#39;/Users/petertao/Library/Caches/pip/http&#39; or its parent
&gt; directory is not owned by the current user and the cache has been
&gt; disabled. Please check the permissions and owner of that directory. If
&gt; executing pip with sudo, you may want sudo&#39;s -H flag.
&gt; 
&gt; The directory &#39;/Users/petertao/Library/Caches/pip&#39; or its parent
&gt; directory is not owned by the current user and caching wheels has been
&gt; disabled. check the permissions and owner of that directory. If
&gt; executing pip with sudo, you may want sudo&#39;s -H flag.

**What does sudo&#39;s -H flag do?**


Content Type	Original Author	Original Content on Stackoverflow
Question	NateW	View Question on Stackoverflow
Solution 1 - Docker	NateW	View Answer on Stackoverflow

Can't use yum inside Docker container running on CentOS

Docker Problem Overview

Docker Solutions

Solution 1 - Docker

Error: Templates should only be responsible for mapping the state to the UI. Avoid placing tags with side-effects in your templates, such as <script>

Can we mount sub-directories of a named volume in docker?

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