Access ARG between stages in Dockerfile

djviking · June 10, 2020, 2:13pm

I am not interested in keeping the JDK11 beyond building the image.
I need the JAVA_HOME from the jdk11 image as an argument within the build process.

It is needed for the path of the Java installation I am using in the COPY statement.

I found an explanation on Docker GitHub that might explain what I want is not possible.

github.com/moby/moby

ARG before FROM in Dockerfile doesn't behave as expected

opened 07:58PM - 16 Jul 17 UTC

closed 10:14PM - 07 Dec 17 UTC

Benjamin-Dobell

area/builder version/17.06

**Description** It's documented that `ARG` can appear before `FROM`, so that …arguments may be substituted into image names etc. Rather than having some `ARG` before and some `ARG` after `FROM`, for consistency I attempted to place all my `ARG` before `FROM`. However, to my surprise (after a lot of debugging) I determined that my arguments are _always_ blank after `FROM`. I believe the meta-arg functionality/refactoring may somehow be responsible: https://github.com/moby/moby/commit/239c53bf836174108dbae445a394a290f5fe2898 **Steps to reproduce the issue:** 1. Produce a Dockerfile such as: ``` ARG environment FROM alpine:3.5 ENV ENVIRONMENT=${environment:-development} RUN echo "$ENVIRONMENT" > /value_of_environment ``` 2. Build the image and run the image, printing the value of `environment` ARG (stored in /value_of_environment): ``` docker run $(docker build -q --build-arg environment=production .) cat /value_of_environment ``` **Describe the results you received:** `development` **Describe the results you expected:** `production` **Additional information you deem important (e.g. issue happens only occasionally):** Altering the `Dockerfile` such that `ARG` comes after `FROM` i.e. ``` FROM alpine:3.5 ARG environment ENV ENVIRONMENT=${environment:-development} RUN echo "$ENVIRONMENT" > /value_of_environment ``` then running again: ``` docker run $(docker build -q --build-arg environment=production .) cat /value_of_environment ``` gives the expected output of `production`. **Output of `docker version`:** ``` Client: Version: 17.06.0-ce API version: 1.30 Go version: go1.8.3 Git commit: 02c1d87 Built: Fri Jun 23 21:31:53 2017 OS/Arch: darwin/amd64 Server: Version: 17.06.0-ce API version: 1.30 (minimum version 1.12) Go version: go1.8.3 Git commit: 02c1d87 Built: Fri Jun 23 21:51:55 2017 OS/Arch: linux/amd64 Experimental: true ``` **Output of `docker info`:** ``` Containers: 59 Running: 0 Paused: 0 Stopped: 59 Images: 370 Server Version: 17.06.0-ce Storage Driver: aufs Root Dir: /var/lib/docker/aufs Backing Filesystem: extfs Dirs: 457 Dirperm1 Supported: true Logging Driver: json-file Cgroup Driver: cgroupfs Plugins: Volume: local Network: bridge host ipvlan macvlan null overlay Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog Swarm: inactive Runtimes: runc Default Runtime: runc Init Binary: docker-init containerd version: cfb82a876ecc11b5ca0977d1733adbe58599088a runc version: 2d41c047c83e09a6d61d464906feb2a2f3c52aa4 init version: 949e6fa Security Options: seccomp Profile: default Kernel Version: 4.9.31-moby Operating System: Alpine Linux v3.5 OSType: linux Architecture: x86_64 CPUs: 4 Total Memory: 5.818GiB Name: moby ID: BCV5:MEMK:BYKI:I2IU:QY2V:5DRM:F2FP:JFAG:SM46:M2WJ:73YV:3KLP Docker Root Dir: /var/lib/docker Debug Mode (client): false Debug Mode (server): true File Descriptors: 20 Goroutines: 40 System Time: 2017-07-16T19:58:09.054157098Z EventsListeners: 1 No Proxy: *.local, 169.254/16 Registry: https://index.docker.io/v1/ Experimental: true Insecure Registries: 127.0.0.0/8 Live Restore Enabled: false ```

Basically, after the FROM instruction all the build arguments are reset and thus aren’t available in the Dockerfile.

Anyone have an idea how I can work around this?

I need the JAVA_HOME environment variable taken in FROM jdk11 into the FROM base.

Would ENV work instead for what I am trying to do.

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Access ARG between stages in Dockerfile

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