Support both AMD64 and ARM64 Promtail binary URLs

[balbirthomas]

Issue

LogProxyConsumer currently only supports AMD64 architectures. Hence it can not install and use Promtail on other architectures such as ARM64. The purpose of this PR is to support both AMD64 and ARM64 architectures and ensure additional architectures can be easily added in the future.

Solution

The following changes were made as part of this refactor.

• The relation data structure with promtail information set by LokiPushApiProvider has been extended so that it includes
  • information for multiple architectures
  • URL and filename of Promtail for each architecture
  • sha256 sum of Promtail zip for each architecture
  • sha256 sum of Promtail binary for each architecture
• All hardcoding of filename and paths for Promtail binaries were removed. The filenames are extracted from relation data provided by the LokiPushApiProvider, in a architecture dependent way. The LogProxyConsumer selects the correct Promtail filename based on its architecture from the choices offered to by the LokiPushApiProvider.
• The _setup_promtail() method has been made idempotent and the check if _is_promtail_installed() has been moved into this method. Hence _setup_promtail() only installs promtail if it has not already been installed.

Context

Explained in "Issue" above.

Testing Instructions

Just deploy Loki and Log proxy consumer and check that logs from promtail are forwarded.

Release Notes

LokiPushApiProvider and LogProxyConsumer objects now support AMD64 and ARM64 architectures for Promtail.

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr

[github-actions]

Libraries are not up to date with their remote counterparts. If this was
not intentional, run charmcraft fetch-libs and commit the updated libs
to your PR branch.

stdout

Library charms.alertmanager_k8s.v0.alertmanager_dispatch was already up to date in version 0.3.                                                                
Library charms.grafana_k8s.v0.grafana_source was already up to date in version 0.9.                                                                            
Library charms.loki_k8s.v0.loki_push_api has local changes, cannot be updated. 
Library charms.observability_libs.v0.kubernetes_service_patch was already up to date in version 0.6.                                                           

stderr