There&#39;s no builtin way for Docker to print the `WORKDIR` during a build. You can inspect the final workdir for an image/layer:

    docker image inspect {image-name} | jq &#39;.[].Config.WorkingDir&#39;

It&#39;s possible to view a Linux containers build steps workdir by printing the shells default working directory:

    RUN pwd

or the shell often stores the working directory in the PWD environment variable 

    RUN echo &quot;$PWD&quot;

If you are using newer versions of dockers BuildKit, stdout will need to be enabled with `--progress=plain`

    docker build --progress=plain . 

There seems some recent change to the `docker build` command, where it hides `stdout` during the build process.

In short use `DOCKER_BUILDKIT=0 docker build` to get the &quot;old&quot; behavior back.

([reference][1])


  [1]: https://stackoverflow.com/a/64805337/16174836

RUN doesn&#39;t print in my IDE console if I use `docker-compose up`.
But CMD does. So try 
 
```CMD pwd```  

In case you have python in the image, this should also work

```CMD [&quot;python&quot;, &quot;-c&quot;, &quot;import os;print(os.getcwd())&quot;]```

Please note, **only** one, **the last CMD command will be executed** in the &quot;container-run&quot; phase. All others will be silently ignored. On the other side, there is a standard piping workaround:

```CMD pwd &amp;&amp; ls```

&gt; The information below may be superfluous if you are trying to understand the error message. Please start off by reading [the answer](https://stackoverflow.com/a/37968229/6292000)
 by **@user707650**.

Using MatPlotLib, I wanted a generalizable script that creates the following from my data. 

A window containing ***a*** subplots arranged so that there are ***b*** subplots per column. I want to be able to change the values of ***a*** and ***b***. 

If I have data for ***2a*** subplots, I want 2 windows, each with the previously described &quot;***a*** subplots arranged according to ***b*** subplots per column&quot;.

The x and y data I am plotting are floats stored in np.arrays and are structured as follows:

 - The x data is always the same for all plots and is of length 5.

         &#39;x_vector&#39;: [0.000, 0.005, 0.010, 0.020, 0.030, 0.040]

 - The y data of all plots are stored in **y_vector** where the data for the first plot is stored at indexes 0 through 5. The data for the second plot is stored at indexes 6 through 11. The third plot gets 12-18, the fourth 19-24, and so on.

In total, for this dataset, I have 91 plots (i.e. 91*6 = 546 values stored in y_vector). 

**Attempt:**

    import matplotlib.pyplot as plt
    
    # Options:
    plots_tot = 14 # Total number of plots. In reality there is going to be 7*13 = 91 plots.
    location_of_ydata = 6 # The values for the n:th plot can be found in the y_vector at index &#39;n*6&#39; through &#39;n*6 + 6&#39;.
    plots_window = 7 # Total number of plots per window.
    rows = 2 # Number of rows, i.e. number of subplots per column.
    
    # Calculating number of columns:
    prim_cols = plots_window / rows
    extra_cols = 0
    if plots_window % rows &gt; 0:
    	extra_cols = 1
    cols = prim_cols + extra_cols
    
    print &#39;cols:&#39;, cols
    print &#39;rows:&#39;, rows
    
    # Plotting:
    n=0
    x=0
    fig, ax = plt.subplots(rows, cols)
    while x &lt;= plots_tot:
    	ax[x].plot(x_vector, y_vector[n:(n+location_of_ydata)], &#39;ro&#39;)
    	if x % plots_window == plots_window - 1:
    		plt.show() # New window for every 7 plots.
    	n = n+location_of_ydata
    	x = x+1

**I get the following error:**

    cols: 4
    rows: 2
    Traceback (most recent call last):
      File &quot;Script.py&quot;, line 222, in &lt;module&gt;
        ax[x].plot(x_vector, y_vector[n:(n+location_of_ydata)], &#39;ro&#39;)
    AttributeError: &#39;numpy.ndarray&#39; object has no attribute &#39;plot&#39;

Axes from plt.subplots() is a &quot;numpy.ndarray&quot; object and has no attribute &quot;plot&quot;

In react components is it preferred to set the initial state in the constructor() or componentWillMount()?

    export default class MyComponent extends React.Component{
      constructor(props){
        super(props);
        this.setState({key: value});
      }
    }

or

    export default class MyComponent extends React.Component{
      componentWillMount(props){
        this.setState({key: value});
      }
    }

set initial react component state in constructor or componentWillMount?

We have a problem with the `WORKDIR` when we building a docker image. Is it possible to print the value of `WORKDIR`?

We tried:

    ECHO ${WORKDIR}

But there is no such instruction `ECHO`

Is it possible to show the `WORKDIR` when building a docker image?

We have a problem with the <code>WORKDIR</code> when we building a docker image. Is it possible to print the value of <code>WORKDIR</code>?
We tried:
<pre><code class="hljs language-bash">ECHO ${WORKDIR}
</code></pre>
But there is no such instruction <code>ECHO</code>

I tried the following command in my Dockerfile: `COPY * /` and got mighty surprised at the result. Seems the naive docker code traverses the directories from the glob and then dumps the each file in the target directory while respectfully ignoring my directory structure. 

At least that is how I understand [this ticket][1] and it certainly corresponds to the result I got. 

I guess the only reason this behavior can still exist must be that there is some other way this should be done. But it is not so easy for a bear of very little brain to understand how, does anyone know?

  [1]: https://github.com/docker/docker/issues/15858

How to copy folders to docker image from Dockerfile?

Is there a best practice on setting up glibc on docker alpine linux base image with correct paths so any spawned process can correctly reference the location of the installed libc libraries?

Is there a best practice on setting up glibc on docker alpine linux base image?

In the docker world, one can easily see logs for docker container (that is, a running image). But during image creation, one usually issues multiple commands. For example npm install commands in node projects. It would be beneficial to see logs for those commands as well. I quickly searched from the documentation, but didn&#39;t find how one can obtain logs for docker image. Is it possible?

How to view logs for a docker image?

I have been digging through the Kubernetes documentation for hours.  I understand the core design, and the notion of services, controllers, pods, etc.  

What I don&#39;t understand, however, is the process in which I can declaratively configure the cluster.  That is, a way for me to write a config file (or a set thereof) to define the makeup, and scaling options of the cloud deployment.  I want to be able to declare which containers I want in which pods, how they will communicate, how they will scale, etc. without running a ton of cli commands.

***Is there [docker-compose][1] functionality for Kubernetes?***

I want my application to be defined in git—to be version controlled–without relying on manual cli interactions. 

Is this possible to do in a concise way?  Is there a reference that is more clear than the official documentation?


  [1]: https://docs.docker.com/compose/overview/

Can Kubernetes be used like Docker Compose?

Lets say I am running a [multiprocessing][1] service inside a docker container spawning multiple processes, would docker use all/multiple cores/CPUs of the host or just one?


  [1]: https://docs.python.org/2/library/multiprocessing.html

How many CPUs does a docker container use?

If I set an environment variable, say `ENV ADDRESSEE=world`, and I want to use it in the entry point script concatenated into a fixed string like:

    ENTRYPOINT [&quot;./greeting&quot;, &quot;--message&quot;, &quot;Hello, world!&quot;]

with `world` being the value of the environment varible, how do I do it? I tried using `&quot;Hello, $ADDRESSEE&quot;` but that doesn&#39;t seem to work, as it takes the `$ADDRESSEE` literally.

How do I use Docker environment variable in ENTRYPOINT array?

I am trying to create a docker image from my docker file which has the following content:

 

    FROM ubuntu:14.04.4
    RUN echo &#39;deb http://private-repo-1.hortonworks.com/HDP/ubuntu14/2.x/updates/2.4.2.0 HDP main&#39; &gt;&gt; /etc/apt/sources.list.d/HDP.list
    RUN echo &#39;deb http://private-repo-1.hortonworks.com/HDP-UTILS-1.1.0.20/repos/ubuntu14 HDP-UTILS main&#39;  &gt;&gt; /etc/apt/sources.list.d/HDP.list
    RUN echo &#39;deb [arch=amd64] https://apt-mo.trafficmanager.net/repos/azurecore/ trusty main&#39; &gt;&gt; /etc/apt/sources.list.d/azure-public-trusty.list
    RUN gpg --keyserver pgp.mit.edu --recv-keys B9733A7A07513CAD
    RUN gpg -a --export 07513CAD | apt-key add -
    RUN gpg --keyserver pgp.mit.edu --recv-keys B02C46DF417A0893
    RUN gpg -a --export 417A0893 | apt-key add -
    RUN apt-get update

which fails with the following error:

    root@sbd-docker:~/ubuntu# docker build -t hdinsight .
    Sending build context to Docker daemon 3.072 kB
    Step 1 : FROM ubuntu:14.04.4
     ---&gt; 8f1bd21bd25c
    Step 2 : RUN echo &#39;deb http://private-repo-1.hortonworks.com/HDP/ubuntu14/2.x/updates/2.4.2.0 HDP main&#39; &gt;&gt; /etc/apt/sources.list.d/HDP.list
     ---&gt; Using cache
     ---&gt; bc23070c0b18
    Step 3 : RUN echo &#39;deb http://private-repo-1.hortonworks.com/HDP-UTILS-1.1.0.20/repos/ubuntu14 HDP-UTILS main&#39;  &gt;&gt; /etc/apt/sources.list.d/HDP.list
     ---&gt; Using cache
     ---&gt; e45c32975e28
    Step 4 : RUN echo &#39;deb [arch=amd64] https://apt-mo.trafficmanager.net/repos/azurecore/ trusty main&#39; &gt;&gt; /etc/apt/sources.list.d/azure-public-trusty.list
     ---&gt; Using cache
     ---&gt; 1659cdcab06e
    Step 5 : RUN gpg --keyserver pgp.mit.edu --recv-keys B9733A7A07513CAD
     ---&gt; Using cache
     ---&gt; ca73b2bfcd21
    Step 6 : RUN gpg -a --export 07513CAD | apt-key add -
      ---&gt; Using cache
      ---&gt; 95596ad10bc9
    Step 7 : RUN gpg --keyserver pgp.mit.edu --recv-keys B02C46DF417A0893
     ---&gt; Using cache
     ---&gt; f497deeef5b5
    Step 8 : RUN gpg -a --export 417A0893 | apt-key add -
     ---&gt; Using cache
     ---&gt; d01dbe7fa02e
    Step 9 : RUN apt-get update
     ---&gt; Running in 89d75799982f
    E: The method driver /usr/lib/apt/methods/https could not be found.
    The command &#39;/bin/sh -c apt-get update&#39; returned a non-zero code: 100
    root@sbd-docker:~/ubuntu#

I am running this on `Ubuntu 14.04.4`.

I tried restarting docker, cleaning up all docker images, installing `apt-transport-https`, but nothing worked.

I dont know whats wrong here.

apt-get update&#39; returned a non-zero code: 100

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. 

Content Type	Original Author	Original Content on Stackoverflow
Question	Freewind	View Question on Stackoverflow
Solution 1 - Docker	Matt	View Answer on Stackoverflow
Solution 2 - Docker	ethergeist	View Answer on Stackoverflow
Solution 3 - Docker	Sergey Skripko	View Answer on Stackoverflow

Is it possible to show the `WORKDIR` when building a docker image?

Docker Problem Overview

Docker Solutions

Solution 1 - Docker

Solution 2 - Docker

Solution 3 - Docker

set initial react component state in constructor or componentWillMount?

Axes from plt.subplots() is a "numpy.ndarray" object and has no attribute "plot"

Attributions