devapp: add ca-certificates to Dockerfile

CL 176257 refactored the Dockerfile to remove the use of gitlock but I
forgot to include ca-certificates here.

Updates golang/go#32272 (fixes maybe)
Updates golang/go#26872

Change-Id: I7b0e3a756bc9805e81e499b8b7d7c6ed0defb871
Reviewed-on: https://go-review.googlesource.com/c/build/+/179077
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/devapp/Dockerfile b/devapp/Dockerfile
index 0431f5d..c785a4c 100644
--- a/devapp/Dockerfile
+++ b/devapp/Dockerfile
@@ -38,6 +38,20 @@
 RUN go install golang.org/x/build/devapp
 
 FROM debian:stretch
+
+# netbase and ca-certificates are needed for dialing TLS.
+# The rest are useful for debugging if somebody needs to exec into the container.
+RUN apt-get update && apt-get install -y \
+	--no-install-recommends \
+	netbase \
+	ca-certificates \
+	curl \
+	strace \
+	procps \
+	lsof \
+	psmisc \
+	&& rm -rf /var/lib/apt/lists/*
+
 COPY --from=builder /go/bin/devapp /
 COPY devapp/static /static
 COPY devapp/templates /templates