Docker: Ignore ARGs without default values #4723
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In #4598 we added support for ARG FROM. However, this assumed that a default value is always specified, when it isn't the code would crash. This is not that common, however: Due to how we parse Dockerfiles, this actually also happened for regular `ARG`s in a Dockerfile, even if it didn't belong to the `FROM`, meaning that any ARG without a default would cause our update to fail.
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| context "arg from" do | ||
| let(:dockerfile_fixture_name) { "arg_from_curls" } | ||
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| describe "with curls" do | ||
| let(:dockerfile_fixture_name) { "arg_from_curls" } | ||
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| key_value = line.delete_prefix("ARG ").split("=") | ||
| next if key_value.count != 2 # The ARG has no default value that we can set | ||
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I'm not sure I fully understand how this piece works. Here we split on =, but the example in the fixture file doesn't have an = so HUB in ARG HUB does not qualify as a default argument?
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You would need to pass it in from the commandline:
docker build --build-arg=HUB=docker.io .
But since Dependabot can't know the value in this case, we don't perform an update
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That makes a lot more sense in context 👍🏾
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Sorry, this still fails, because I forgot to update the file-updater... |
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For anyone who stumbles across this later, ☝️ is tracked in #4725. |
In #4598 we added
support for ARG FROM. However, this assumed that a default value is
always specified, when it isn't the code would crash.
This is not that common, however:
Due to how we parse Dockerfiles, this actually also happened for regular
ARGs in a Dockerfile, even if it didn't belong to theFROM, meaningthat any ARG without a default would cause our update to fail.