Composing a customized RHEL system image with proxy server

Issue

• How to compose a customized RHEL system image when a proxy server is required.

• composer-cli blueprints depsolve NAME fails with following error

  DNF error occured: RepoError: Error occurred when setting up repo: Failed to download metadata for repo '0': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried blueprint: NAME
  

• composer-cli blueprints depsolve NAME fails with following in journal/syslog

  image-builder dnf[###]: Error: Failed to download metadata for repo 'rhel-8-for-x86_64-appstream-rpms': Cannot download repomd.xml: Curl error (28): Timeout was reached for https://cdn.redhat.com/content/dist/rhel8/8/x86_64/appstream/os/repodata/repomd.xml  [Connection timed out after 30003 milliseconds]
  

• composer-cli compose start NAME fails with error code 28

  Traceback (most recent call last):
    File "/run/osbuild/lib/stages/org.osbuild.rpm", line 161, in <module>
      r = main(args["tree"], args["sources"], args["options"])
    File "/run/osbuild/lib/stages/org.osbuild.rpm", line 101, in main
      osbuild.sources.get("org.osbuild.files", checksums)
    File "/run/osbuild/lib/osbuild/sources.py", line 87, in get
      raise RuntimeError(f"{source}: " + reply["error"])
  RuntimeError: org.osbuild.files: curl: error downloading {'url': 'https://cdn.redhat.com/content/dist/.../PACKAGE.rpm', 'secrets': {'ssl_ca_cert': '/etc/rhsm/ca/FILE.pem', 'ssl_client_key': '/etc/pki/entitlement/FILE-key.pem', 'ssl_client_cert': '/etc/pki/entitlement/FILE.pem'}}: error code 28