Bump MSRV due to pulled in version of impl-trait-for-tuples dependency needing support for the 2021 Rust edition.

.github/workflows/ci.yml

@@ -43,10 +43,10 @@ jobs:
       matrix:
         os: [ubuntu-latest]
 
-        # Test against Rust 1.47.0 because in build.rs we say that is the oldest supported version.
+        # Test against Rust 1.56.0 because in build.rs we say that is the oldest supported version.
         # Test against beta Rust to get early warning of any problems that might occur with the upcoming Rust release.
         # Order: oldest Rust to newest Rust.
-        rust: [1.47.0, stable, beta]
+        rust: [1.56.0, stable, beta]
 
         # Test with no features, default features ("") and all except UI tests.
         # Order: fewest features to most features.

Dockerfile

@@ -2,7 +2,7 @@
 # Make the base image configurable so that the E2E test can use a base image
 # with a prepopulated Cargo build cache to accelerate the build process.
 # Use Ubuntu 16.04 because this is what the Travis CI Krill build uses.
-ARG BASE_IMG=alpine:3.13
+ARG BASE_IMG=alpine:3.15
 
 #
 # -- stage 1: build krill and krillc
@@ -25,7 +25,7 @@ RUN CARGO_HTTP_MULTIPLEXING=false cargo build --target x86_64-alpine-linux-musl
 #             scripts needed to run Krill, and not the things needed to build
 #             it.
 #
-FROM alpine:3.12
+FROM alpine:3.15
 COPY --from=build /tmp/krill/target/x86_64-alpine-linux-musl/release/krill /usr/local/bin/
 COPY --from=build /tmp/krill/target/x86_64-alpine-linux-musl/release/krillc /usr/local/bin/
 COPY --from=build /tmp/krill/target/x86_64-alpine-linux-musl/release/krillup /usr/local/bin/

build.rs

@@ -3,9 +3,9 @@ use rustc_version::{version, Version};
 
 fn main() {
     let version = version().expect("Failed to get rustc version.");
-    if version < Version::parse("1.47.0").unwrap() {
+    if version < Version::parse("1.56.0").unwrap() {
         eprintln!(
-            "\n\nAt least Rust version 1.47 is required.\n\
+            "\n\nAt least Rust version 1.56 is required.\n\
              Version {} is used for building.\n\
              Build aborted.\n\n",
             version