test: add end-to-end testing framework (#5435)

Partial fix for #5291. For details, see [README.md](https://github.com/tendermint/tendermint/blob/erik/e2e-tests/test/e2e/README.md) and [RFC-001](https://github.com/tendermint/tendermint/blob/master/docs/rfc/rfc-001-end-to-end-testing.md).

This only includes a single test case under `test/e2e/tests/`, as a proof of concept - additional test cases will be submitted separately. A randomized testnet generator will also be submitted separately, there a currently just a handful of static testnets under `test/e2e/networks/`. This will eventually replace the current P2P tests and run in CI.

test/e2e/docker/Dockerfile

@@ -0,0 +1,32 @@
+# We need to build in a Linux environment to support C libraries, e.g. RocksDB.
+# We use Debian instead of Alpine, so that we can use binary database packages
+# instead of spending time compiling them.
+FROM golang:1.15
+
+RUN apt-get update -y && apt-get upgrade -y
+RUN apt-get install -y libleveldb-dev librocksdb-dev
+
+# Set up build directory /src/tendermint
+ENV TENDERMINT_BUILD_OPTIONS badgerdb,boltdb,cleveldb,rocksdb
+WORKDIR /src/tendermint
+
+# Fetch dependencies separately (for layer caching)
+COPY go.mod go.sum ./
+RUN go mod download
+
+# Build Tendermint and install into /usr/bin/tendermint
+COPY . .
+RUN make build && cp build/tendermint /usr/bin/tendermint
+COPY test/e2e/docker/entrypoint* /usr/bin/
+RUN cd test/e2e && make app && cp build/app /usr/bin/app
+
+# Set up runtime directory. We don't use a separate runtime image since we need
+# e.g. leveldb and rocksdb which are already installed in the build image.
+WORKDIR /tendermint
+VOLUME /tendermint
+ENV TMHOME=/tendermint
+
+EXPOSE 26656 26657 26660
+ENTRYPOINT ["/usr/bin/entrypoint"]
+CMD ["node"]
+STOPSIGNAL SIGTERM

test/e2e/docker/entrypoint

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+#!/usr/bin/env bash
+
+# Forcibly remove any stray UNIX sockets left behind from previous runs
+rm -rf /var/run/privval.sock /var/run/app.sock
+
+/usr/bin/app /tendermint/config/app.toml &
+
+sleep 1
+
+/usr/bin/tendermint "$@"

test/e2e/docker/entrypoint-builtin

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+#!/usr/bin/env bash
+
+# Forcibly remove any stray UNIX sockets left behind from previous runs
+rm -rf /var/run/privval.sock /var/run/app.sock
+
+/usr/bin/app /tendermint/config/app.toml