I am trying to read a large file one line at a time. I found [a question on Quora][1] that dealt with the subject but I&#39;m missing some connections to make the whole thing fit together.

     var Lazy=require(&quot;lazy&quot;);
     new Lazy(process.stdin)
         .lines
         .forEach(
              function(line) { 
	              console.log(line.toString()); 
	          }
     );
     process.stdin.resume();


The bit that I&#39;d like to figure out is how I might read one line at a time from a file instead of STDIN as in this sample.

I tried: 

     fs.open(&#39;./VeryBigFile.csv&#39;, &#39;r&#39;, &#39;0666&#39;, Process);

     function Process(err, fd) {
     	if (err) throw err;
        // DO lazy read 
     }

but it&#39;s not working.  I know that in a pinch I could fall back to using something like PHP, but I would like to figure this out.  

I don&#39;t think the other answer would work as the file is much larger than the server I&#39;m running it on has memory for. 

  [1]: http://www.quora.com/What-is-the-best-way-to-read-a-file-line-by-line-in-node-js

Read a file one line at a time in node.js?

When writing CSS, is there a particular rule or guideline that should be used in deciding when to use `margin` and when to use `padding`?


When to use margin vs padding in CSS

So I have a Nginx running inside a docker container, I have a mysql running on the host system, I want to connect to the MySql from within my container. MySql is only binding to the localhost device.

Is there any way to connect to this MySql or any other program on localhost from within this docker container?

This question is different from &quot;How to get the IP address of the docker host from inside a docker container&quot; due to the fact that the IP address of the docker host could be the public IP or the private IP in the network which may or may not be reachable from within the docker container (I mean public IP if hosted at AWS or something). Even if you have the IP address of the docker host it does not mean you can connect to docker host from within the container given that IP address as your Docker network may be overlay, host, bridge, macvlan, none etc which restricts the reachability of that IP address.

From inside of a Docker container, how do I connect to the localhost of the machine?

So I have a Nginx running inside a docker container, I have a mysql running on the host system, I want to connect to the MySql from within my container. MySql is only binding to the localhost device.
Is there any way to connect to this MySql or any other program on localhost from within this docker container?
This question is different from "How to get the IP address of the docker host from inside a docker container" due to the fact that the IP address of the docker host could be the public IP or the private IP in the network which may or may not be reachable from within the docker container (I mean public IP if hosted at AWS or something). Even if you have the IP address of the docker host it does not mean you can connect to docker host from within the container given that IP address as your Docker network may be overlay, host, bridge, macvlan, none etc which restricts the reachability of that IP address.

I made a simple image through Dockerfile from Fedora (initially 320 MB).

Added Nano (this tiny editor of 1MB size), and the size of the image has risen to 530 MB. I&#39;ve added Git on top of that (30-ish MB), and then my image size sky-rockets to 830 MB. 

Isn&#39;t that insane?

I&#39;ve tried to export and import container to remove history/intermediate images. This effort saved up to 25 MB, now my image size is 804 MB. I&#39;ve also tried to run many commands on one `RUN`, but still I&#39;m getting the same initial 830MB.

I&#39;m having my doubts if it is worth to use Docker at all. I mean, I barely installed anything and I&#39;m hitting 1GB over. If I will have to add some serious stuff like a database and so on I might run out of disk space.

Anyone suffers from ridiculous size of images? How do you deal with it?

Unless my Dockerfile is horribly incorrect?

    FROM fedora:latest
    MAINTAINER Me NotYou &lt;email@dot.com&gt;
    RUN yum -y install nano
    RUN yum -y install git

but it&#39;s hard to imagine what could go wrong in here.


Why are Docker container images so large?

I try to locate one specific tag for a Docker image. How can I do it on the command line? I want to avoid downloading all the images and then removing the unneeded ones.

In the official Ubuntu release, https://registry.hub.docker.com/_/ubuntu/, there are several tags (release for it), while when I search it on the command line,

    user@ubuntu:~$ docker search ubuntu | grep ^ubuntu
    ubuntu              Official Ubuntu base image                          354
    ubuntu-upstart      Upstart is an event-based replacement for ...   7
    ubuntufan/ping                                                0
    ubuntu-debootstrap                                                   0

Also in the help of command line `search` https://docs.docker.com/engine/reference/commandline/search/, no clue how it can work?

Is it possible in the `docker search` command?

If I use a raw command to search via the [Docker registry API][1], then the information can be fetched:

       $ curl https://registry.hub.docker.com//v1/repositories/ubuntu/tags | python -mjson.tool
       [
        {
            &quot;layer&quot;: &quot;ef83896b&quot;,
            &quot;name&quot;: &quot;latest&quot;
        },
        .....
        {
            &quot;layer&quot;: &quot;463ff6be&quot;,
            &quot;name&quot;: &quot;raring&quot;
        },
        {
            &quot;layer&quot;: &quot;195eb90b&quot;,
            &quot;name&quot;: &quot;saucy&quot;
        },
        {
            &quot;layer&quot;: &quot;ef83896b&quot;,
            &quot;name&quot;: &quot;trusty&quot;
        }
    ]

  [1]: https://docs.docker.com/registry/spec/api/#tags



How can I find a Docker image with a specific tag in Docker registry on the Docker command line?

I&#39;m wondering where Docker&#39;s images are exactly stored to in my local host machine.
Can I share my Docker-Image without using the ```Docker-Hub``` or a ```Dockerfile``` but the &#39;real&#39; Docker-Image? And what is exactly happening when I &#39;push&#39; my Docker-Image to Docker-Hub?


How to share my Docker-Image without using the Docker-Hub?

In my `Dockerfile` I&#39;ve got :

    ADD ../../myapp.war /opt/tomcat7/webapps/

That file exists as `ls ../../myapp.war` returns me the correct file but when I execute `sudo docker build -t myapp .` I&#39;ve got :

	Step 1 : ADD ../../myapp.war /opt/tomcat7/webapps/
	2014/07/02 19:18:09 ../../myapp.war: no such file or directory

Does somebody know why and how to do it correctly?

Docker: adding a file from a parent directory

I&#39;m writing a very simple bash script to quickly check that my container still builds and starts correctly and that the app inside responds to requests.

Sometimes `docker run` fails, e.g. because the port I&#39;m trying to bind the container to is already allocated. But when this happens `docker run`&#39;s exit code is still 0 so I can&#39;t use the exit code. How can I check programmatically that the container got started correctly?

The solutions I&#39;m considering are:

 - parse the output for errors
 - `docker ps` to see if the container is running

but these both seem a little overkill and ugly. Am I missing a better way to check whether `docker run` succeeded?

How to detect if docker run succeeded programmatically?

I have recently started migrating to Docker 1.9 and Docker-Compose 1.5&#39;s networking features to replace using links.

So far with links there were no problems with nginx connecting to my php5-fpm fastcgi server located in a different server in one group via docker-compose. Newly though when I run `docker-compose --x-networking up` my php-fpm, mongo and nginx containers boot up, however nginx quits straight away with `[emerg] 1#1: host not found in upstream &quot;waapi_php_1&quot; in /etc/nginx/conf.d/default.conf:16`

However, if I run the docker-compose command again while the php and mongo containers are running (nginx exited), nginx starts and works fine from then on.

This is my `docker-compose.yml` file:

    nginx:
      image: nginx
      ports:
        - &quot;42080:80&quot;
      volumes:
        - ./config/docker/nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
    
    php:
      build: config/docker/php
      ports:
        - &quot;42022:22&quot;
      volumes:
        - .:/var/www/html
      env_file: config/docker/php/.env.development
    
    mongo:
      image: mongo
      ports:
        - &quot;42017:27017&quot;
      volumes:
        - /var/mongodata/wa-api:/data/db
      command: --smallfiles

This is my `default.conf` for nginx:

    server {
        listen  80;
    
        root /var/www/test;
    
        error_log /dev/stdout debug;
        access_log /dev/stdout;
    
        location / {
            # try to serve file directly, fallback to app.php
            try_files $uri /index.php$is_args$args;
        }
    
        location ~ ^/.+\.php(/|$) {
            # Referencing the php service host (Docker)
            fastcgi_pass waapi_php_1:9000;
    
            fastcgi_split_path_info ^(.+\.php)(/.*)$;
            include fastcgi_params;
    
            # We must reference the document_root of the external server ourselves here.
            fastcgi_param SCRIPT_FILENAME /var/www/html/public$fastcgi_script_name;
    
            fastcgi_param HTTPS off;
        }
    }

How can I get nginx to work with only a single docker-compose call?

Docker Networking - nginx: [emerg] host not found in upstream

With 1.9, is there a way to start a container directly with two or more network interfaces?

You can do it after the container is started with &quot;docker network connect&quot;, but it means the process is already running and might miss the creation of the new one.

Start container with multiple network interfaces

I have a situation to restrict internet access of the container in load balancer network. for example in that below picture

[![easy for your reference][1]][1]

Only **container4** connects to the Internet; other **three** only communicate through **container4** with the outside world. For example if **container1** needs smtp support, it will forward smtp request to **container4** to get access.

No container other than **container4** should be allowed to access the Internet directly! This should be enforced on Docker level.

I believe it will be configurable on **docker network creation**, can any one explain how to achieve this?


  [1]: http://i.stack.imgur.com/tChKt.png

Restrict Internet Access - Docker Container

I&#39;m learning docker. I see those two terms make me confuse. For example here is a docker-compose that defined two services `redis` and `web-app`.

    services:
      redis:
        container_name: redis
        image: redis:latest
        ports:
          - &quot;6379:6379&quot;
        networks:
          - lognet
    
      app:
        container_name: web-app
        build:
          context: .
          dockerfile: Dockerfile
        ports:
          - &quot;3000:3000&quot;
        volumes:
          - &quot;.:/webapp&quot;
        links:
          - redis
        networks:
          - lognet
    
    networks:
      lognet:
        driver: bridge

This `docker-compose` file defines a bridge network named lognet and all services will connect to this network. As I understand, this action makes those services can see others. So why app service still need to link to redis service in above case.

Thanks

docker-compose: difference between networks and links

Containers in a host &quot;suddenly&quot; loses connection to outside-world containers. However, some hosts were refreshed and suddenly we had the following situation:

1. The host can communicate with other hosts.
2. Containers running in the host cannot communicate with other hosts.

Here&#39;s an example:

    [root@pprdespap322 deploy]# ping ci.docker.company.net
    PING pprdespap324.corp.company.net (10.137.55.22) 56(84) bytes of data.
    64 bytes from pprdespap324.corp.company.net (10.137.55.22): icmp_seq=1 ttl=64 time=0.282 ms
    64 bytes from pprdespap324.corp.company.net (10.137.55.22): icmp_seq=2 ttl=64 time=0.341 ms
    ^C
    --- pprdespap324.corp.company.net ping statistics ---
    2 packets transmitted, 2 received, 0% packet loss, time 1001ms
    rtt min/avg/max/mdev = 0.282/0.311/0.341/0.034 ms

Now, from the container itself, we cannot ping the same host:

    [root@pprdespap322 deploy]# docker run -ti quay.io/coreos/registry ping ci.docker.company.net
    WARNING: IPv4 forwarding is disabled. Networking will not work.
    ping: unknown host ci.docker.company.net


The first time I saw this warning was in the initial versions of Docker... Having Docker 1.9.1 and 1.10.3, How to solve this problem?

From inside of a Docker container, how do I connect to the localhost of the machine?

Docker Problem Overview

Docker Solutions

When to use margin vs padding in CSS

Read a file one line at a time in node.js?

Attributions