podman build

redhat/notes/2024/2024.12.podman.build.md

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+# podman build & ps
+
+We build contaimer image using podman build, but sometimes we encounter issues with the build process that can cause the build to fail, sometimes the script in the dockerfile will write logfile to local directory which will be deleted or overwritten after the podman build exit.
+
+To see the content of such log files generated during the build process, we need some tips to access the logs files. What we will do, is to run container using the intermediary cache image which is created during the build process, and access the logfile in the container.
+
+```bash
+
+mkdir -p /data/tmp
+
+cd /data/tmp
+
+# we create a dockerfile, which have multiple RUN
+# each RUN will create an intermedary image layers
+cat << EOF > Dockerfile
+FROM docker.io/rockylinux:9
+
+RUN echo 'test' > /tmp/wzh.test
+
+RUN sleep 99999999
+
+EOF
+
+# during podman build, we can see the intermedary layers being created
+podman build -t myimage:remove ./
+# STEP 1/3: FROM docker.io/rockylinux:9
+# STEP 2/3: RUN echo 'test' > /tmp/wzh.test
+# --> 3fb515b1a25c
+# STEP 3/3: RUN sleep 99999999
+
+# no container created
+podman ps -a
+# nothing
+
+# but the intermediary image has been created
+podman image ls
+# REPOSITORY                    TAG         IMAGE ID      CREATED         SIZE
+# <none>                        <none>      3fb515b1a25c  20 seconds ago  181 MB
+# ......
+
+# we can run a container from the intermediary image
+# to access the logfile
+podman run --rm 3fb515b1a25c cat /tmp/wzh.test
+# test
+
+```
+
+# end