chore: Dockerfile: build browser image from chromium-swiftshader-alpine

The new base image is built at
https://github.com/grafana/chromium-swiftshader-alpine, and should allow
us to both get chromium updates as PRs, while at the same time being
stable so an outdated version does not break builds in the foreseeable
future.

Dockerfile

@@ -5,9 +5,7 @@ RUN apk --no-cache add ca-certificates-bundle
 # Second stage copies the binaries, configuration and also the
 # certificates from the first stage.
 
-ARG TARGETPLATFORM
-
-FROM --platform=$TARGETPLATFORM alpine:3.20.3 AS release
+FROM alpine:3.20.3 AS release
 ARG TARGETOS
 ARG TARGETARCH
 ARG HOST_DIST=$TARGETOS-$TARGETARCH
@@ -21,18 +19,9 @@ ENTRYPOINT ["/usr/local/bin/synthetic-monitoring-agent"]
 
 # Third stage copies the setup from the base agent and
 # additionally installs Chromium to support browser checks.
-FROM --platform=$TARGETPLATFORM alpine:3.20.3 AS with-browser
-
-ARG TARGETARCH
+FROM ghcr.io/grafana/chromium-swiftshader-alpine:131.0.6778.85-r0-3.20.3 AS with-browser
 
-# Renovate updates the pinned packages below.
-# The --repository arg is required for renovate to know which alpine repo it should look for updates in.
-# To keep the renovate regex simple, only keep one package installation per line.
-# Furthermore, we split this into two lines to allow for the arm64 and amd64 versions of chromium to be different, as 
-# they have drifted in the past.
-RUN apk --no-cache add --repository community tini=0.19.0-r3
-RUN [[ "$TARGETARCH" != "amd64" ]] || apk --no-cache add --repository community --arch x86_64 chromium-swiftshader=131.0.6778.69-r0
-RUN [[ "$TARGETARCH" != "arm64" ]] || apk --no-cache add --repository community --arch aarch64 chromium-swiftshader=131.0.6778.69-r0
+RUN apk --no-cache add --repository community tini
 
 COPY --from=release /usr/local/bin/synthetic-monitoring-agent /usr/local/bin/synthetic-monitoring-agent
 COPY --from=release /usr/local/bin/sm-k6 /usr/local/bin/sm-k6

Dockerfile.build

@@ -19,21 +19,9 @@ ENTRYPOINT ["/usr/local/bin/synthetic-monitoring-agent"]
 
 # Third stage copies the setup from the base agent and
 # additionally installs Chromium to support browser checks.
-FROM alpine:3.20.3 AS with-browser
-ARG TARGETOS
-ARG TARGETARCH
+FROM ghcr.io/grafana/chromium-swiftshader-alpine:131.0.6778.85-r0-3.20.3 AS with-browser
 
-# Renovate updates the pinned packages below.
-# The --repository arg is required for renovate to know which alpine repo it should look for updates in.
-# The --arch flag is necessary so that it knows which architecture to target.
-# To keep the renovate regex simple, only keep one package installation per line.
-#
-# Alpine does not have a consistent set of packages across all the
-# architectures, so we have to install different versions depending on which
-# one we are targeting.
-RUN apk --no-cache add --repository community tini=0.19.0-r3
-RUN if test "$TARGETARCH" = "amd64" ; then apk --no-cache add --repository community --arch x86_64  chromium-swiftshader=131.0.6778.69-r0 ; fi
-RUN if test "$TARGETARCH" = "arm64" ; then apk --no-cache add --repository community --arch aarch64 chromium-swiftshader=131.0.6778.69-r0 ; fi
+RUN apk --no-cache add --repository community tini
 
 COPY --from=release /usr/local/bin/synthetic-monitoring-agent /usr/local/bin/synthetic-monitoring-agent
 COPY --from=release /usr/local/bin/sm-k6 /usr/local/bin/sm-k6