Fact "docker": undefined method []' for nil:NilClass on RHEL-8(docker-podman)

[dusharu]

Describe the Bug

Error in facter when use podman-docker.rpm on RHEL-8

puppet agent -t

Info: Using configured environment 'develop'
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Error: Facter: error while resolving custom fact "docker": undefined method `[]' for nil:NilClass  #<--- this ERROR
Info: Caching catalog for prod-bis-mmisc1.scartel.dc
Info: Applying configuration version '1621517818'
Notice: Applied catalog in 8.78 seconds

Expected Behavior

Add support for podman to /opt/puppetlabs/puppet/cache/lib/facter/docker.rb

/opt/puppetlabs/puppet/bin/facter  --custom-dir /opt/puppetlabs/puppet/cache/lib/facter/ docker

# Expected - json with docker info
# in fact -  nothing

Steps to Reproduce

install podman-docker.noarch from repo os-rhel8-appstream
run puppet agent -t
or run /opt/puppetlabs/puppet/bin/facter --custom-dir /opt/puppetlabs/puppet/cache/lib/facter/ -d docker

Environment

• OS: Red Hat Enterprise Linux release 8.3 (Ootpa)
• puppet: 5.5.22
• podman version 2.2.1
• facter: 3.11.14 (commit 2f05c0b208c0848bc0052ac7abf772754f4b79da)

Additional Context

[BarnumD]

I'm having similar problems on Windows and Ubuntu after upgrading to 4.1.1 from and older version.

[cswarren]

I'm also having this error show up on Centos 7 systems that don't have docker installed. New behavior in 4.1.1.

[github-actions]

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[silug]

This appears to have been fixed with #773.

[makewhatis]

This was broken in a different way for us when going from C7 to C8, 773 did not fix. Looks like in the network inspect json output, podman returns a key for "id" in lowercase, and docker returns "Id", pascal case.

This is where I had to change it, fwiw. I'm sure there is a better way of doing this...so I'm just leaving this for anyone that hits this.

index b7cb379b54..d3a674b0c6 100644
--- a/docker/lib/facter/docker.rb
+++ b/docker/lib/facter/docker.rb
@@ -92,7 +92,12 @@ Facter.add(:docker) do
           docker_network_names.each do |network|
             inspect = JSON.parse(Facter::Util::Resolution.exec("#{docker_command} network inspect #{network}"))
             docker['network'][network] = inspect[0]
-            network_id = docker['network'][network]['Id'][0..11]
+            # support docker and podman. Podman outputs lowercase id
+            if docker['network'][network].key?('id')
+              network_id = docker['network'][network]['id'][0..11]
+            else
+              network_id = docker['network'][network]['Id'][0..11]
+            end

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